Machines, such as for construction and earthmoving as well as other applications, may include a variety of hydraulically actuated implements and/or tools, for example buckets, shovels, blades, scrapers, shears, etc., which may be mounted on a movable linkage. Control of the implements and/or linkage preferably include a timely response to operator input. Such hydraulic systems may include an actuator having a piston disposed within a hollow actuator body. A rod is attached to the piston and extends out of one end of the actuator body. The piston divides the compartment in the hollow actuator body into a rod-end chamber and a head-end chamber, wherein the rod may be extended and/or retracted by introducing pressurized fluid into the head-end chamber and/or the rod-end chamber, respectively, and evacuating fluid from the other chamber.
Generally, responsiveness (i.e. the time required for a rod to extend and/or retract) is proportional to the fluid flow rate and power is proportional to fluid pressure. Generally, under full power operation, fluid is introduced into one chamber while evacuating fluid from the other chamber to a drain or reservoir. Response time in a hydraulic actuator may be improved by directing fluid from the chamber being evacuated to the chamber being filled to increase flow and thus increase responsiveness (i.e. decrease response time). Operating conditions for a hydraulic actuator may be such that at certain times
To increase the responsiveness, some hydraulic systems include a regeneration circuit configured to direct flow from one chamber to the other. For example, EP1580437A1 discloses a hydraulic actuator including a piston rod defining three chambers within the hydraulic actuator, a valve configuration, and a first and second supply line configured for extending and retracting the piston rod, respectively. EP1580437A1 discloses that the valve configuration and the first and second supply lines operate to extend and retract the piston rod by directing hydraulic fluid to and from the various chambers based on the differential pressure between the first supply line and the second supply line. The hydraulic system of the present disclosure includes a dedicated fluid supply line for extending the rod and a separate dedicated fluid supply line for retracting the rod.
In another example, JP2009047237A discloses a pair of hydraulic actuators capable of consistent performance without respect to outside forces. In this example, a first hydraulic actuator and a second hydraulic actuator are connected to allow fluid to be introduced from the first actuator body to the second actuator boy. In contrast, the present disclosure is directed to a hydraulic actuator and valve arrangement that allows for internal bi-directional regeneration within a single actuator.
In another example of a multi-chambered actuator, JP2000329110A discloses a hydraulic cylinder including a piston rod defining three chambers in fluid communication. The hydraulic cylinder includes a heating element attached to the end of the rod by an insulating material. The three chambers provide a fluid circulation circuit within the actuator. In the present disclosure, the chambers of the hydraulic actuator are separate to allow selective pressurization/depressurization of individual chambers depending on predetermined conditions.